I vote w/MG & Lexie on this, sort of --
I like to stomp BINs and place opening bids to hopefully prevent sellers from ending auctions early. HOWEVER, unlike MG & Lexie, I AM paranoid! So I cheat, sort of. I don't want people looking at my bidding history of my sniping ebay ID to find out I'm a sniper. So I stomp BINs with a DIFFERENT ebay ID, then swoop in with my max bid snipe from my sniping ID to hopefully win. I also occasionally DO BINs and will use my BIN stomping ID for that, too.
Oh yeah, I DON'T use one ID to bid up items listed by other....